The present invention is directed to a process for converting a liquid chlorosilane mixture of predominantly trichlorosilane and silicon tetrachloride, contaminated with various metal chlorides and minor amounts of metals, into environmentally acceptable products in an efficient manner. In the course of the purification of metallurgical silicon to electronic purity as described, for example, in U.S. Pat. No. 4,519,999 (incorporated herein by reference), essentially all impurities present initially in the silicon feed are rejected in the course of purification in mixture with chlorosilanes, e.g., trichlorosilane and silicon tetrachloride. Such impurities amount to about 2% by weight of the metallurgical grade silicon starting material and, when metallurgical grade silicon is reacted with hydrogen chloride to form trichlorosilane, as noted in U.S. Pat. No. 4,519,999, the rejected impurities admixed with chlorosilanes consist primarily, by weight percent of the mixture, of from 0.1 to 5% in the aggregate of chlorides of aluminum, iron, titanium, and up to 20% in the aggregate of elemental iron, silicon and aluminum. The aforementioned impurities are conventionally removed from the process system by dilution in a liquid mixture stream of predominantly trichlorosilane and silicon tetrachloride. Particulate impurities in the mixture are inherently smaller in size than 40 microns, e.g., 10-40 microns. To dispose of the contaminated mixture, it has been a common practice, prior to this invention, to add the mixture to water, hydrolyzing the mixture constituents to oxides, and co-producing a dilute hydrochloric acid, which is then neutralized with a suitable base. To accomplish this reaction in a manner such as that the reaction vessel will not become plugged with the silica solids formed by hydrolysis, extremely high levels of agitation have been required along with very large amounts of water. Burning techniques have also been proposed for waste disposal as described in U.S. Pat. No. 4,519,999 noted above. Such burning techniques are effective in some circumstances, but ordinarily require expensive equipment and fuel.